[lustre-devel] [PATCH 21/29] lustre: osc_cache: don't drop a lock we didn't take - two

[Andreas Dilger]

> On Jan 8, 2019, at 23:24, NeilBrown <neilb at suse.com> wrote:
> 
> osc_check_rpcs() drops a lock that it was called with, which can make
> it harder to understand the code.
> 
> It is only called from one place, and that places takes the lock just
> to all this function.

(typo) "call"

> So instead, take the lock at the start of the function,
> and drop it at the end.
> This makes the code easier to follow.
> 
> Signed-off-by: NeilBrown <neilb at suse.com>

Reviewed-by: Andreas Dilger <adilger at whamcloud.com>

> ---
> drivers/staging/lustre/lustre/osc/osc_cache.c |    5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/lustre/lustre/osc/osc_cache.c b/drivers/staging/lustre/lustre/osc/osc_cache.c
> index 863884cac028..b2ad6a15014e 100644
> --- a/drivers/staging/lustre/lustre/osc/osc_cache.c
> +++ b/drivers/staging/lustre/lustre/osc/osc_cache.c
> @@ -2187,11 +2187,11 @@ static struct osc_object *osc_next_obj(struct client_obd *cli)
> 
> /* called with the loi list lock held */
> static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli)
> -	__must_hold(&cli->cl_loi_list_lock)
> {
> 	struct osc_object *osc;
> 	int rc = 0;
> 
> +	spin_lock(&cli->cl_loi_list_lock);
> 	while ((osc = osc_next_obj(cli)) != NULL) {
> 		struct cl_object *obj = osc2cl(osc);
> 		struct lu_ref_link link;
> @@ -2247,6 +2247,7 @@ static void osc_check_rpcs(const struct lu_env *env, struct client_obd *cli)
> 
> 		spin_lock(&cli->cl_loi_list_lock);
> 	}
> +	spin_unlock(&cli->cl_loi_list_lock);
> }
> 
> static int osc_io_unplug0(const struct lu_env *env, struct client_obd *cli,
> @@ -2258,9 +2259,7 @@ static int osc_io_unplug0(const struct lu_env *env, struct client_obd *cli,
> 		return 0;
> 
> 	if (!async) {
> -		spin_lock(&cli->cl_loi_list_lock);
> 		osc_check_rpcs(env, cli);
> -		spin_unlock(&cli->cl_loi_list_lock);
> 	} else {
> 		CDEBUG(D_CACHE, "Queue writeback work for client %p.\n", cli);
> 		LASSERT(cli->cl_writeback_work);
> 
> 

Cheers, Andreas
---
Andreas Dilger
CTO Whamcloud